Production of artificial materials



Patented Mar. 24, I942 PRODUCTION OF ARTIFICIAL MATERIALS Henry Dreyfus, London, England, assignor to Celanese Corporation of America, a corporation of Delaware No Drawing. Application November 30, 1939, Se-

rial No. 306,904. 1939 12 Claims.

This invention relates to the production of artificial materials and more particularly to the treatment of staple fibres having a basis of an organic derivative of cellulose.

According to the invention staple fibres which have a basis of an organic derivative of cellulose and which have been produced by cutting filamentary materials are subjected, while in a condition in which they are substantially free to contract, to the action of a crinkling medium which is substantially, and preferably entirely, free from water. It is found that, by'this treatment the fibers acquire a crinkled form which greatly improves their spinning qualities.

' The cut staple fibres which are treated may be produced from any suitable filamentary material having a, basis of an organic derivative of cellulose, particularly cellulose acetate. For example, continuous filaments or waste filaments may be cut into short lengths of 1 /2 to 2 inches or more, or into longer fibres of 4, 7, 9 or 12 inches or more, according to the use for which they are required. The staple fibres may be produced in a number of ways, e. g. by means of the methods and apparatus described in U. S. Patents Nos. 2,220,022, 2,079,094 and 2,010,078 and British Patents Nos. 394,702, 357,565, 317,026 and 317,025, or by cut ting the bundles of filaments produced according to the process of U. S. Patent No. 2,067,251.

The invention is of particular value in con- In Great Britain January 6,

nection with staple fibreswhich have been progeously have been produced by cutting continuous filaments which have been stretched, e. g. to 200, 500 or 1000% or more of their original length, especially in the presence of wet steam or hot water, as described, -for example, in British Patents Nos. 438,584, 438,585, 438,586, 438,587, 438,655 and 438,656. The continuous filaments may, however, have been stretched by other processes. For example, subsequent to their production by dry or wet spinning processes they may have been stretched in the presence of softening agents such as, for example, dioxane or acetone. Alternatively, when produced by wet spinning processes, filaments may have been stretched in a coagulating bath containing a high proportion-of asoftening agent, e. g. glycol monoacetate.

While particular reference has been made above to cellulose acetate as the basis of the staple fibres it is to be understood that the fibres may have .ibasis of other organic derivatives of cellulose,

propionate, cellulose butyrate, and cellulose aceto-propionate, ethers, for example, ethyl cellulose, methyl cellulose, benzyl cellulose and oxyethyl cellulose, and ether-esters.

The active agents in the crinkling media employed according to the invention are preferably latent solvents, i. e. swelling agents which, though incapable in the pure condition of dissolving the cellulose derivative, become solvents when mixed with a comparatively small proportion of another liquid. Among such latent solvents are, for example, methylene chloride, ethylene chloride and ethyl acetate. The swelling agents should, in general, have their action modified by being diluted with one or more relatively inert liquids.

Such diluents may be immiscible with water, e. g.

mixtures containing 60-70% of methylene ch10 ride and 40-30% of benzene. Other mixtures giving especially useful results arethose of 2-20% by volume of ethyl acetate and 98-80% of ethyl alcohol. The actual concentration of the active agent employed will depend upon the nature of the treated material and upon the degree of crinkling which is required.

The temperature of treatment for any particu-' lar treatment medium and treated material may be varied according to the degree of crinkling which it is desired to impart to the fibres, since at higher temperatures the crinkle is more proe. g. other esters such as, for example, cellulose 'nounced than at lower ones.

The results are found to be most generally satisfactory when a temperature of the order of 25 C. is employed in conjunction with the crinkling media specified above.

The fibres are preferably crinkled by immersing slivers or other bundles which it is desired to maintain in form throughout the treatment, it is preferable to support them during the treatment. This may be done, for example, by passing them through a bath of the crinkling medium or by spraying them with the medium while they are supported on a travelling band, e. g. a continuous wire-gauze band or felt sheet, and allowing the bundles to remain on the band under the action of the medium for an appropriate time. After treatment the medium may be run off from the I fibres and the'latter dried by evaporation, e. g. in

a stream of warm air, due regard being paid to the nature of the swelling agent and of any diluents employed so that adhesion of the fibres ing and/or de-electrifyingagents are applied to the fibres before carding and spinning was to facilitate these operations. Such agents may be, for example, hygroscopic polyhydric alcohols or hygroscopic salts. The application of the conditioning and/or de-electrifying agents may be carried out simultaneously with the treatment with the crinkling medium, provided that the agents are soluble or dispersible in the particular medium employed. For example, a proportion of about 3-6% of a suitable agent may be dissolved in the crinkling medium and the resulting solution employed for crinkling according to the invention.- I

If desired, fibres having a basis of an organic ester of cellulose may be saponified either wholly,

partially or superficially to modify their dyeing properties and/or their ironing point. Partial or superficial saponification may be carried out before or after treatment with the crinkling me dium; for example superficially saponified staple fibres may be treated with the crinkling medium, and in this case the outer'coating of cellulose or of lower ester of cellulose tends to prevent coalescence of the fibres.

The following examples illustrate the invention but are not to be regarded as limiting it in any way:

Example I Staple fibres, cut from continuous cellulose acetate filaments which have been stretched in wet steam to 200% of their original length, are

volume) is run in. After thoroughly agitating for 15 minutes at 20 C., the liquid is run of! and the fibres dried in a stream of air at C.

The products are similar to those of Example I.

Having described my invention, what I desire to secure by Letters Patent is:

1. Process for improving the properties of staple fibres having a basis of an organic derivative of cellulose and produced by cutting filamenta'ry materials, which comprises subjecting the fibers, while in a condition'in which they are substantially free to contract, to the action of a medium which comprises a latent solvent for the celllulose derivative and which is substantially free from water.

2. Process for improving the properties of staple fibers having a basis of an organic derivative of cellulose and produced by cutting filamentary materials, which comprises subjecting the fibers, while in a condition in which they are substantially free to contract, to the action of a medium which comprises methylene chloride diluted with a hydrophobe organic liquid and which is substantially free from water.

3. Process for improving the properties of staple fibers having a basis of an organic derivative of cellulose and produced by cutting filamentary materials, which comprises subjecting the fibers, while in a condition in which they are substantially free to contract, to the action of a medium which comprises ethylene dichloride diluted with a hydrophobe organic liquid and which is substantially free from water.

4. Process for improving the properties of sta ple fibers having a basis of an organic derivative of cellulose and produced by cutting filamentary materials, which comprises subjecting the fibers,

while in a condition in which they are substantially free to contract, to the action of a medium which comprises ethyl ,acetate diluted with a lower aliphatic alcohol and which is substantially free from water.

5. Process for improving the properties of staple fibers having a basis of cellulose acetate and produced by cutting filamentary materials, which comprises subjecting the fibers, while in a condition in which they are substantially free to contract, to the action of a medium which comprises methylene chloride diluted with a hydrophobe organic liquid and which is substantially free from water.

placed in a container as a loose mass and about Example II Staple fibres, cut from continuous cellulose acetate filaments which have been stretched in wet steam to 200% of their original length, are placed in a container as a loose mass and about 12 times their weight of a mixture of 7% ethyl acetate and 93% ethyl alcohol (percentage by 6. Process for improving the properties of staple fibers having a basis of cellulose acetate and produced by cutting filamentary materials, which comprises subjecting the fibers, while in a condition in which they, are substantially free to contract, to the action of a medium which comprises ethylene dichloride diluted with a hydrophobe organic liquid and which is substantially free from water.

7. Process for improving the properties of staple fibers having a basis of cellulose acetate and produced by cutting filamentary materials, which comprises subjecting the fibers,'while in a condition in which they are substantially free to contract, to the action of a medium which to contract, to the action of a medium consisting of 2-20 parts by volume of ethyl acetate in admixture with 98-80 parts by volume of ethyl alcohol.

10. Process for improving the properties of staple fibers having a basis of an organic derivative of cellulose and produced by cutting filamentary materials which have been stretched to at least 200% of their original length in the presence of a stretch-assisting medium, which comprises subjecting the fibers-while in a condition in which they are substantially free to contract, to the action of a medium which comprises a latent solvent for the cellulose derivative and which is substantially free from water.

v 3 11. Process for improving the properties of staple fibers having a basis of cellulose acetate and produced by cutting filamentary materials a which have been stretched to at least 200% of their original length in the presence of a stretchassisting medium, which comprises subjecting the fibers, while in a condition in which they are substantially free to contract, to the action of a medium consisting of 50-70 parts by volume of methylene chloride in admixture with 50-30 parts by volume of benzene.

12. Process for improving the properties of staple fibers having a basis of cellulose acetate and produced by cutting filamentary materials which have been stretched to at least 200% of their original length in the presence of a stretchassisting medium, which comprises subjecting the fibers, while in a condition in which they are substantially free to contract, to the action 0! a medium consisting or 2-20 parts by volume of ethyl acetate in admixture with 98-80 parts by volume of ethyl alcohol. a

HENRY DREYFUS. 

